EFPI sensors are mostly applied to measure pressure, strain or temperature. For instance, the EFPI employed in measuring distance is usually used for detecting the micro or nano displacement. However there are always large or small displacement such as exceeding 1 mm or 1 cm in practical structures. The sensors in the prior art for measuring large distance are most based on the electric principle, in which the potentiometer parts are used to convert the mechanical displacement to a resistance or voltage output according to their linear or nonlinear functional relation, and then deduce displacement through output signal. Therefore, these foregoing mentioned sensors for distance measurement are easily impacted by temperature or electromagnetic and thus the temperature compensate and anti-interference processing are necessary. But using optic fiber as the sensor can eliminate many disadvantages such as the effects from electromagnetic.